number (from 1 to 6) – it indicates the degree of development of the embryo:
1 – the blastocyst cavity is less than half of the whole embryo
2 – the blastocyst cavity is larger than half of the whole embryo
3 – full blastocyst, the cavity fills almost the entire embryo
4 – a developed blastocyst, the cavity includes the entire embryo, a thin membrane
5 – the blastocyst breaks out of the shell
6 – blastocyst without a shell
the first letter (A, B, C), denoting the quality of the intracellular mass, from which the embryo will develop:
A – many cells, densely packed
B – several cells, freely grouped
C – very few cells
the second letter (A, B, C), which denotes the quality of the trophectoderm (TE), which will ensure the attachment of the embryo to the endometrium and develop into the placenta:
A – many cells, form a single layer
B – few cells, form free epithelium
C – very few large cells